/****************************************************************************
 *
 * Copyright 2016 Samsung Electronics All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
 * either express or implied. See the License for the specific
 * language governing permissions and limitations under the License.
 *
 ****************************************************************************/
/*
 * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the Institute nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * This file is built upon the file: src/arch/rtxc/netif/sioslip.c
 *
 * Author: Magnus Ivarsson <magnus.ivarsson(at)volvo.com>
 *         Simon Goldschmidt
 *
 * Usage: This netif can be used in three ways:
 *        1) For NO_SYS==0, an RX thread can be used which blocks on sio_read()
 *           until data is received.
 *        2) In your main loop, call slipif_poll() to check for new RX bytes,
 *           completed packets are fed into netif->input().
 *        3) Call slipif_received_byte[s]() from your serial RX ISR and
 *           slipif_process_rxqueue() from your main loop. ISR level decodes
 *           packets and puts completed packets on a queue which is fed into
 *           the stack from the main loop (needs SYS_LIGHTWEIGHT_PROT for
 *           pbuf_alloc to work on ISR level!).
 *
 */

/**
 * @file
 * SLIP Interface
 *
 */

/*
 * This is an arch independent SLIP netif. The specific serial hooks must be
 * provided by another file. They are sio_open, sio_read/sio_tryread and sio_send
 */

#include "lwip/netif/slipif.h"
#include "lwip/opt.h"

#if LWIP_HAVE_SLIPIF

#include "lwip/def.h"
#include "lwip/pbuf.h"
#include "lwip/stats.h"
#include "lwip/snmp.h"
#include "lwip/sio.h"
#include "lwip/sys.h"

#define SLIP_END     0xC0		/* 0300: start and end of every packet */
#define SLIP_ESC     0xDB		/* 0333: escape start (one byte escaped data follows) */
#define SLIP_ESC_END 0xDC		/* 0334: following escape: original byte is 0xC0 (END) */
#define SLIP_ESC_ESC 0xDD		/* 0335: following escape: original byte is 0xDB (ESC) */

/** Maximum packet size that is received by this netif */
#ifndef SLIP_MAX_SIZE
#define SLIP_MAX_SIZE 1500
#endif

/** Define this to the interface speed for SNMP
 * (sio_fd is the sio_fd_t returned by sio_open).
 * The default value of zero means 'unknown'.
 */
#ifndef SLIP_SIO_SPEED
#define SLIP_SIO_SPEED(sio_fd) 0
#endif

enum slipif_recv_state {
	SLIP_RECV_NORMAL,
	SLIP_RECV_ESCAPE,
};

struct slipif_priv {
	sio_fd_t sd;
	/* q is the whole pbuf chain for a packet, p is the current pbuf in the chain */
	struct pbuf *p, *q;
	u8_t state;
	u16_t i, recved;
#if SLIP_RX_FROM_ISR
	struct pbuf *rxpackets;
#endif
};

/**
 * Send a pbuf doing the necessary SLIP encapsulation
 *
 * Uses the serial layer's sio_send()
 *
 * @param netif the lwip network interface structure for this slipif
 * @param p the pbuf chaing packet to send
 * @param ipaddr the ip address to send the packet to (not used for slipif)
 * @return always returns ERR_OK since the serial layer does not provide return values
 */
err_t slipif_output(struct netif *netif, struct pbuf *p, const ip4_addr_t *ipaddr)
{
	struct slipif_priv *priv;
	struct pbuf *q;
	u16_t i;
	u8_t c;

	LWIP_ASSERT("netif != NULL", (netif != NULL));
	LWIP_ASSERT("netif->state != NULL", (netif->state != NULL));
	LWIP_ASSERT("p != NULL", (p != NULL));

	LWIP_UNUSED_ARG(ipaddr);

	LWIP_DEBUGF(SLIP_DEBUG, ("slipif_output(%" U16_F "): sending %" U16_F " bytes\n", (u16_t) netif->num, p->tot_len));
	priv = netif->state;

	/* Send pbuf out on the serial I/O device. */
	/* Start with packet delimiter. */
	sio_send(SLIP_END, priv->sd);

	for (q = p; q != NULL; q = q->next) {
		for (i = 0; i < q->len; i++) {
			c = ((u8_t *) q->payload)[i];
			switch (c) {
			case SLIP_END:
				/* need to escape this byte (0xC0 -> 0xDB, 0xDC) */
				sio_send(SLIP_ESC, priv->sd);
				sio_send(SLIP_ESC_END, priv->sd);
				break;
			case SLIP_ESC:
				/* need to escape this byte (0xDB -> 0xDB, 0xDD) */
				sio_send(SLIP_ESC, priv->sd);
				sio_send(SLIP_ESC_ESC, priv->sd);
				break;
			default:
				/* normal byte - no need for escaping */
				sio_send(c, priv->sd);
				break;
			}
		}
	}
	/* End with packet delimiter. */
	sio_send(SLIP_END, priv->sd);
	return ERR_OK;
}

/**
 * Handle the incoming SLIP stream character by character
 *
 * @param netif the lwip network interface structure for this slipif
 * @param c received character (multiple calls to this function will
 *        return a complete packet, NULL is returned before - used for polling)
 * @return The IP packet when SLIP_END is received
 */
static struct pbuf *slipif_rxbyte(struct netif *netif, u8_t c)
{
	struct slipif_priv *priv;
	struct pbuf *t;

	LWIP_ASSERT("netif != NULL", (netif != NULL));
	LWIP_ASSERT("netif->state != NULL", (netif->state != NULL));

	priv = netif->state;

	switch (priv->state) {
	case SLIP_RECV_NORMAL:
		switch (c) {
		case SLIP_END:
			if (priv->recved > 0) {
				/* Received whole packet. */
				/* Trim the pbuf to the size of the received packet. */
				pbuf_realloc(priv->q, priv->recved);

				LINK_STATS_INC(link.recv);

				LWIP_DEBUGF(SLIP_DEBUG, ("slipif: Got packet (%" U16_F " bytes)\n", priv->recved));
				t = priv->q;
				priv->p = priv->q = NULL;
				priv->i = priv->recved = 0;
				return t;
			}
			return NULL;
		case SLIP_ESC:
			priv->state = SLIP_RECV_ESCAPE;
			return NULL;
		}						/* end switch (c) */
		break;
	case SLIP_RECV_ESCAPE:
		/* un-escape END or ESC bytes, leave other bytes
		   (although that would be a protocol error) */
		switch (c) {
		case SLIP_ESC_END:
			c = SLIP_END;
			break;
		case SLIP_ESC_ESC:
			c = SLIP_ESC;
			break;
		}
		priv->state = SLIP_RECV_NORMAL;
		break;
	}							/* end switch (priv->state) */

	/* byte received, packet not yet completely received */
	if (priv->p == NULL) {
		/* allocate a new pbuf */
		LWIP_DEBUGF(SLIP_DEBUG, ("slipif_input: alloc\n"));
		priv->p = pbuf_alloc(PBUF_LINK, (PBUF_POOL_BUFSIZE - PBUF_LINK_HLEN), PBUF_POOL);

		if (priv->p == NULL) {
			LINK_STATS_INC(link.drop);
			LWIP_DEBUGF(SLIP_DEBUG, ("slipif_input: no new pbuf! (DROP)\n"));
			/* don't process any further since we got no pbuf to receive to */
			return NULL;
		}

		if (priv->q != NULL) {
			/* 'chain' the pbuf to the existing chain */
			pbuf_cat(priv->q, priv->p);
		} else {
			/* p is the first pbuf in the chain */
			priv->q = priv->p;
		}
	}

	/* this automatically drops bytes if > SLIP_MAX_SIZE */
	if ((priv->p != NULL) && (priv->recved <= SLIP_MAX_SIZE)) {
		((u8_t *) priv->p->payload)[priv->i] = c;
		priv->recved++;
		priv->i++;
		if (priv->i >= priv->p->len) {
			/* on to the next pbuf */
			priv->i = 0;
			if (priv->p->next != NULL && priv->p->next->len > 0) {
				/* p is a chain, on to the next in the chain */
				priv->p = priv->p->next;
			} else {
				/* p is a single pbuf, set it to NULL so next time a new
				 * pbuf is allocated */
				priv->p = NULL;
			}
		}
	}
	return NULL;
}

/** Like slipif_rxbyte, but passes completed packets to netif->input
 *
 * @param netif The lwip network interface structure for this slipif
 * @param data received character
 */
static void slipif_rxbyte_input(struct netif *netif, u8_t c)
{
	struct pbuf *p;
	p = slipif_rxbyte(netif, c);
	if (p != NULL) {
		if (netif->input(p, netif) != ERR_OK) {
			pbuf_free(p);
		}
	}
}

#if SLIP_USE_RX_THREAD
/**
 * The SLIP input thread.
 *
 * Feed the IP layer with incoming packets
 *
 * @param nf the lwip network interface structure for this slipif
 */
static void slipif_loop_thread(void *nf)
{
	u8_t c;
	struct netif *netif = (struct netif *)nf;
	struct slipif_priv *priv = (struct slipif_priv *)netif->state;

	while (1) {
		if (sio_read(priv->sd, &c, 1) > 0) {
			slipif_rxbyte_input(netif, c);
		}
	}
}
#endif							/* SLIP_USE_RX_THREAD */

/**
 * SLIP netif initialization
 *
 * Call the arch specific sio_open and remember
 * the opened device in the state field of the netif.
 *
 * @param netif the lwip network interface structure for this slipif
 * @return ERR_OK if serial line could be opened,
 *         ERR_MEM if no memory could be allocated,
 *         ERR_IF is serial line couldn't be opened
 *
 * @note netif->num must contain the number of the serial port to open
 *       (0 by default). If netif->state is != NULL, it is interpreted as an
 *       u8_t pointer pointing to the serial port number instead of netif->num.
 *
 */
err_t slipif_init(struct netif *netif)
{
	struct slipif_priv *priv;
	u8_t sio_num;

	LWIP_DEBUGF(SLIP_DEBUG, ("slipif_init: netif->num=%" U16_F "\n", (u16_t) netif->num));

	/* Allocate private data */
	priv = (struct slipif_priv *)mem_malloc(sizeof(struct slipif_priv));
	if (!priv) {
		return ERR_MEM;
	}

	netif->name[0] = 's';
	netif->name[1] = 'l';
	snprintf(netif->d_ifname, 6, "%c%c%d", netif->name[0], netif->name[1], netif->num);

	netif->output = slipif_output;
	netif->mtu = SLIP_MAX_SIZE;

	/* netif->state or netif->num contain the port number */
	if (netif->state != NULL) {
		sio_num = *(u8_t *) netif->state;
	} else {
		sio_num = netif->num;
	}
	/* Try to open the serial port. */
	priv->sd = sio_open(sio_num);
	if (!priv->sd) {
		/* Opening the serial port failed. */
		mem_free(priv);
		return ERR_IF;
	}

	/* Initialize private data */
	priv->p = NULL;
	priv->q = NULL;
	priv->state = SLIP_RECV_NORMAL;
	priv->i = 0;
	priv->recved = 0;
#if SLIP_RX_FROM_ISR
	priv->rxpackets = NULL;
#endif

	netif->state = priv;

	/* initialize the snmp variables and counters inside the struct netif */
	NETIF_INIT_SNMP(netif, snmp_ifType_slip, SLIP_SIO_SPEED(priv->sd));

#if SLIP_USE_RX_THREAD
	/* Create a thread to poll the serial line. */
	sys_thread_new(SLIPIF_THREAD_NAME, slipif_loop_thread, netif, SLIPIF_THREAD_STACKSIZE, SLIPIF_THREAD_PRIO);
#endif							/* SLIP_USE_RX_THREAD */
	return ERR_OK;
}

/**
 * Polls the serial device and feeds the IP layer with incoming packets.
 *
 * @param netif The lwip network interface structure for this slipif
 */
void slipif_poll(struct netif *netif)
{
	u8_t c;
	struct slipif_priv *priv;

	LWIP_ASSERT("netif != NULL", (netif != NULL));
	LWIP_ASSERT("netif->state != NULL", (netif->state != NULL));

	priv = (struct slipif_priv *)netif->state;

	while (sio_tryread(priv->sd, &c, 1) > 0) {
		slipif_rxbyte_input(netif, c);
	}
}

#if SLIP_RX_FROM_ISR
/**
 * Feeds the IP layer with incoming packets that were receive
 *
 * @param netif The lwip network interface structure for this slipif
 */
void slipif_process_rxqueue(struct netif *netif)
{
	struct slipif_priv *priv;
	SYS_ARCH_DECL_PROTECT(old_level);

	LWIP_ASSERT("netif != NULL", (netif != NULL));
	LWIP_ASSERT("netif->state != NULL", (netif->state != NULL));

	priv = (struct slipif_priv *)netif->state;

	SYS_ARCH_PROTECT(old_level);
	while (priv->rxpackets != NULL) {
		struct pbuf *p = priv->rxpackets;
#if SLIP_RX_QUEUE
		/* dequeue packet */
		struct pbuf *q = p;
		while ((q->len != q->tot_len) && (q->next != NULL)) {
			q = q->next;
		}
		priv->rxpackets = q->next;
		q->next = NULL;
#else							/* SLIP_RX_QUEUE */
		priv->rxpackets = NULL;
#endif							/* SLIP_RX_QUEUE */
		SYS_ARCH_UNPROTECT(old_level);
		if (netif->input(p, netif) != ERR_OK) {
			pbuf_free(p);
		}
		SYS_ARCH_PROTECT(old_level);
	}
}

/** Like slipif_rxbyte, but queues completed packets.
 *
 * @param netif The lwip network interface structure for this slipif
 * @param data Received serial byte
 */
static void slipif_rxbyte_enqueue(struct netif *netif, u8_t data)
{
	struct pbuf *p;
	struct slipif_priv *priv = (struct slipif_priv *)netif->state;
	SYS_ARCH_DECL_PROTECT(old_level);

	p = slipif_rxbyte(netif, data);
	if (p != NULL) {
		SYS_ARCH_PROTECT(old_level);
		if (priv->rxpackets != NULL) {
#if SLIP_RX_QUEUE
			/* queue multiple pbufs */
			struct pbuf *q = p;
			while (q->next != NULL) {
				q = q->next;
			}
			q->next = p;
		} else {
#else							/* SLIP_RX_QUEUE */
			pbuf_free(priv->rxpackets);
		}
		{
#endif							/* SLIP_RX_QUEUE */
			priv->rxpackets = p;
		}
		SYS_ARCH_UNPROTECT(old_level);
	}
}

/**
 * Process a received byte, completed packets are put on a queue that is
 * fed into IP through slipif_process_rxqueue().
 *
 * This function can be called from ISR if SYS_LIGHTWEIGHT_PROT is enabled.
 *
 * @param netif The lwip network interface structure for this slipif
 * @param data received character
 */
void slipif_received_byte(struct netif *netif, u8_t data)
{
	LWIP_ASSERT("netif != NULL", (netif != NULL));
	LWIP_ASSERT("netif->state != NULL", (netif->state != NULL));
	slipif_rxbyte_enqueue(netif, data);
}

/**
 * Process multiple received byte, completed packets are put on a queue that is
 * fed into IP through slipif_process_rxqueue().
 *
 * This function can be called from ISR if SYS_LIGHTWEIGHT_PROT is enabled.
 *
 * @param netif The lwip network interface structure for this slipif
 * @param data received character
 * @param len Number of received characters
 */
void slipif_received_bytes(struct netif *netif, u8_t *data, u8_t len)
{
	u8_t i;
	u8_t *rxdata = data;
	LWIP_ASSERT("netif != NULL", (netif != NULL));
	LWIP_ASSERT("netif->state != NULL", (netif->state != NULL));

	for (i = 0; i < len; i++, rxdata++) {
		slipif_rxbyte_enqueue(netif, *rxdata);
	}
}
#endif							/* SLIP_RX_FROM_ISR */

#endif							/* LWIP_HAVE_SLIPIF */
